This invention generally relates to a seal between a fixed member and a movable member. More particularly, this invention relates to a finger seal for an exhaust duct assembly.
A gas turbine engine typically includes an exhaust duct for directing exhaust gases. Many exhaust duct assemblies include a movable portion for selectively directing the exhaust gases. Such exhaust duct assemblies includes a fixed portion and a movable portion. A seal is required between the fixed and movable portions to prevent intrusion of exhaust gases through the exhaust nozzle assembly at the interface between the fixed and movable portions.
The seal is typically provided with a plurality of fingers that are formed by a corresponding plurality of slots. The slots and finger configuration provide for flexing and expansion of the movable member relative to the fixed portion. Disadvantageously, the slots create leak paths through which exhaust gases can intrude. Known seals utilize staggered slot configurations to prevent leakage. Such staggered slots are of limited success as leak paths may still form. A known seal includes a cloth between inner and outer sheets that covers the slots. The cloth is fabricated from a temperature resistant material such as Nextel hi-temp ceramic fabric. Disadvantageously, cloth degrades and frays over time. Further the use of cloth complicates manufacture and assembly.
Accordingly it is desirable to design and develop an improved seal for an exhaust nozzle for sealing between a fixed portion and a movable portion that improves manufacturability and durability.